A pressurized product conventionally consists of a container, usually a metal can, which contains a product to be dispensed and a propellant and further includes a valve for controlling the flow of the product to be dispensed by the propellant. The pressurized container typically has the propellant supplied thereto by one of two process.
The first process is the under-the-valve-cup process. The under-the-valve-cup process supplies the propellant to the container before the mounting cup is affixed to the container. This process generally has known drawbacks and shortcomings with the major disadvantage of the under-the-valve-cup process being that it typically has a great loss of the propellant in comparison to the second process, i.e. the pressure filling process. In recent years, there has been a significant trend toward the pressure filling process for filling cans or containers. Currently, a majority of the billions of aerosol containers, which are filled yearly, utilize the pressure filling process.
According to this pressure filling process, the propellant is filled through the valve and then an actuator is subsequently installed on the valve. Alternatively, the container can be filled or charged with the actuator already installed on the valve.
The later pressure filling process is historically known as the button-on-filling (BOF) process. The advantage of the BOF process is that the purchaser of the valves is able to eliminate the step of installing the actuator on the valve, during the production operation, as it has already been previously installed by the valve assembly manufacturer.
One major difficulty encountered in pressurizing a container is achieving a sufficient seal between the filling or charging head, the actuator or spray button and the valve/mounting cup. Past designs employed a special sealing configuration located on the skirt of the actuator facing the top surface of the mounting cup. The pressure required for efficiently filling a container can reach as high as 60 atmospheres (900 psig). To compensate for such high pressures, the actuator recently has been made of a relatively soft material, such as polyethylene, in order to facilitate achieving a suitable seal between the actuator and the top portion of the mounting cup. The need to achieve an improved seal, during pressurization, is more important now because the pressurizing component (e.g. the gas) has been changed, in most manufacturing process, from chlorofluorocarbon (CFC) to hydrocarbons, which are flammable.
One drawback associated with using a softer material to manufacture the actuator is that the softer material has forced a compromise with respect to other functional aspects and considerations of the valve assembly. The softer material requires that a thicker walled, heavier spray actuator to be molded at slower production rates and at higher production costs. The use of the softer material also increases the cost of the actuators and the costs of the injection mold design and the construction as well as the maintenance of the injection molding equipment.
Despite various past efforts, directed at providing an adequate seal between the actuator and the mounting cup, it is still frequently necessary, during pressurization of a container, to increase the downward force of the filling or charging head to seal properly the actuator with the mounting cup. The resulting shortcoming is that the increased load may cause the mounting cup to be depressed excessively, thereby resulting in permanent deformation of the mounting cup. The excessive depression of the mounting cup pedestal may, in turn, produce unwanted side effects, e.g. leakage of the valve, etc.
A further problem of the prior art filling processes is that they tend to employ actuator designs which have one or more areas or cavities, within the interior of the actuator, which can trap and/or store a small quantity of the pressurized charging components and render it difficult to purge such trapped pressurized charging components from the actuator during a subsequent purging step. These trapped pressurized charging components are then immediately released directly into the production facility atmosphere, following completion of the charging process and separation of the charging head from the actuator. The direct release of the trapped pressurized charging components in the production facility atmosphere poses a safety hazard to the production workers and the environment.